Get all operators in the plan that have no predecessors. @return all operators in the plan that have no predecessors, or an empty list if the plan is empty.
()
| 48 | * an empty list if the plan is empty. |
| 49 | */ |
| 50 | public List<Operator> getSources(); |
| 51 | |
| 52 | /** |
| 53 | * Get all operators in the plan that have no successors. |
no outgoing calls